I checked and it's the default for ImageReady, which is apparently the transfer point for the Web images. That is, the files for the Internet should not have empty spaces, so the program inserts hyphens. I always use either compact names or underscores when saving for the web, so I never encountered it before. You can also go to IR, on the File menu open File Saving and tell it to put in the underscores or spaces. But since the server will just have to put the space symbol in, it's better for you to decide how the name will look. I still don't understand why the thumbnails behave like they do. Are you saving in full dimensions?

-- erlik